In the electrical trades, it is frequently required to expand existing electrical box configurations to meet new construction material requirements and methodologies, and at the same time, conform to existing governing codes. With the current commercially available electrical boxes, this is a costly and time consuming task.
Electrical junction boxes are used in building construction and are conventionally installed on the stud walls of a space in a building under construction. Typically, the electrical junction boxes are designed to allow electrical power wires passing through the walls to connect with a structure mounted in or on a wall. For example, electrical junction boxes are designed to provide a rigid and stationary housing for electrical junctions such as where electrical receptacles and switches are connected to electrical wires and where there is normally some uninsulated or dangerous circuit wiring at the exposed connections.
The National Electrical Code, NEC 314.16(b), provides an electrical box volume allowance requirement per conductor. For example, 12 American wire gauge (AWG) wiring requires 2.25 cubic inch per conductor and 14 AWG wiring requires 2.0 cubic inch per conductor. There are commonly 3 conductors per wire and 3 wires per electrical box. Thus, a conventional 12 AWG box would require 20.25 ci and a conventional 14 AWG box would require 18 ci.
One of the earliest patents for an insulated stay-in-place formwork for concrete was registered in the early 1940s. The first ICF forms were developed in the late 1960s. ICF construction had steadily increased since the 1970s though it was initially hampered by lack of awareness, building codes, and confusion caused by many different manufacturers selling slightly different designs rather than focusing on industry standardization.
According to the U.S. Department of Housing and Urban Development, Office of Policy Development and Research, ICF construction costs 3% to 5% more than conventional construction. In some cases, experienced contractors report that electrical costs are on average $3.50 per square foot for conventional wiring and about $4.50 per square foot for ICF construction. ICF type construction is considered better around the world since energy conservation is of global concern. ICF was introduced over 50 years ago and identified as a substantial benefit to the planet yet presently it costs more.
To meet current building codes, there have been adaptations to increase the electrical box volume. One such example is a telescopic electrical box, in U.S. Pat. No. 3,622,029, that extends the box to the side to increase the number of wires that can fit within a smaller finish box. In another, a Universal extension expands the depth of the metal box. See, U.S. Pat. No. 3,955,701. However, the state of the art does not resolve the problem of the removal of ICF foam material or extend into the concrete or provide for a self-adjusting and locking 2-part compressing electrical box, as described herein, nor does it address additional issues caused by ICF building requirements.
ICF wall foam limits the depth possible for electrical boxes. For example, when a box is installed in 2.625 inch thick foam with a mud ring, a net 18 ci is available for the box. This volume does not allow for more than three 14-AWG wires or two 12-AWG wires. In contrast, in this single box example, the ICF electrical box of the present disclosure nets 36 ci, allowing for five 12-AWG or six 14-AWG.
Most current electrical box installations in ICF walls are not conforming to size because they are limited to the thickness of the foam they are mounted in, after the concrete is installed. Additionally, wires pass through site-cut channels through the foam insulation which must be refilled with liquid foam then trimmed after the foam dries.
Most electrical boxes are installed by electricians, after the ICF walls are erected and filled with concrete. The alternative to securing wires, in accordance with NEC 300.4, without substantial effort to attach the wires to the concrete, is to use electrical conduit or metallic-shielded wire. Metallic-shielded wire costs far more than polyvinyl chloride (PVC) conduit and electrical metallic tubes (EMT), and is not permitted to be used in poured concrete applications. EMT fittings cost even more than PVC.
Another method of wiring is to use an electrical box that is contained within the foam and then attached to conduit that sweeps into the concrete. ICF builders often use traditional electrical boxes that will fit into the depth of the ICF foam or similar electrical boxes with grips that extend into the sides of the foam. These boxes are still limited to the depth of the foam and leave an unprofessional appearance due to the array of necessary site-cut channels which need to be covered by the finish wall, such as sheet rock.
Current standards are such that boxes cannot always conform with regulations without extensive alterations to conform to the desired use in ICF applications. As used herein, “ICF” or “foam”, includes, but is not limited to, a surface, material, wall, partition, etc., for which this invention may be applied as it is anticipated that other building materials may be developed which could benefit from the improved electrical boxes described herein.
Currently, a substantial time investment, expense, and job completion delays are common due to the wait for an electrical contractor after the walls are complete. Most electrical boxes cannot be installed before the wall is finished due to the weight of wet concrete pushing them out; and the conventional boxes do not extend beyond the foam into the concrete. Metallic-shielded wire can be used within the ICF foam yet costs more for material and labor and leaves an unprofessional appearance and a mess to clean up as well as a need to refill the foam and then cut the hardened foam once dried. Additionally, current electrical boxes are not easily attachable to the foam, they do not extend into the concrete, nor could these traditional boxes sustain the weight of concrete in their current design or conform to building code.